As the device for producing or examining semiconductors including an etching device, a chemical vapor deposition device and the like, heaters or wafer probers and the like using substrates made of metal such as stainless steel or aluminum alloy, have been conventionally used.
However, heaters made of metal have problems that they have poor temperature control characteristics and they are heavy and bulky since they are thick; and also have another problem that they have poor corrosion resistance to corrosive gases.
In order to solve such problems, heaters which use ceramic such as aluminum nitride have been developed in place of heaters made of metal.
Since such ceramic heaters have the advantage that a warp and the like of ceramic substrates can be prevented even if they are not made so thick due to high rigidity thereof, they are especially suitable for wafer probers or electrostatic chucks.
In recent years, as the semiconductor wafer becomes larger and the diameter thereof becomes larger, the diameter of ceramic substrates used in electrostatic chucks and the like used for producing or examining of semiconductor wafers are required to be bigger so as to put the enlarged semiconductor wafers thereon. Thus, for example, a hot plate having a diameter of 300 mm and a thickness of 17 mm composed of aluminum nitride ceramic is disclosed in JP Kokai Hei 11-74064 and so on.